A total of 58 patients were treated in the study. The overall response rate (ORR) in patients treated with 500 mg of ofatumumab (n=29) was 90%, including 24% complete remissions (CR), and 45% complete remissions/unconfirmed (CRu). In patients treated with 1000 mg of ofatumumab (n=29), the ORR was 100% including 38% CR, and 17% CRu."

Source: Genmab

Wow! 90% response rates are pretty much unheralded in a cancer trial, so I checked out their development partner, GSK, to see what they had to say:

"The overall response rate (ORR) in the 1000 mg treatment arm was 10%, including one complete response and 8 partial responses. In addition, 50% (43) of patients in the 1000 mg treatment arm had stable disease. The overall response rate in the total population was 11%."

A very different story or perhaps a different perspective from two partners seeing the same thing differently. The market reacted promptly and the news sent shares of the Danish biotech down 30 percent on August 18, as investors realized the negative clinical news meant Genmab will not receive an expected milestone payment from GSK related to this indication.

The partnership deal, among the most expensive licensing transactions of the time, promised milestones of over $1 billion. As far as I can tell, GSK paid $102 million in December 2006 in up-front cash and made an equity investment worth over three times that for exclusive rights to the compound, which is in trials for a variety of indications.

As for how the two companies managed to interpret the data differently, I'm not sure what went wrong there, but the difference between 90% and 10% is quite a lot by anyone's reckoning.

Still, an ODAC panel recommended that it should be approved earlier this year and the FDA is expected to make a final decision in October. The new trial data may well make it harder to either gain approval, or even if it does, make any headway against Genentech's Rituxan with those kind of response rates.

Watch this space, as they say, for the next instalment in the story.

{Update:}

Little did I know when I wrote this post the other day that there would indeed be a rapid revision to the story, courtesy of my own haste and folly!

The good folks at GSK kindly alerted me to the fact that the statements relate to two completely different studies, hence the difference in the data. Of course, this makes a big difference! My bad.

So, for clarity, here's what the data across three different trials actually shows:

407 Study – Front-Line Chronic Lymphocytic Leukemia (CLL)

In early August, results from a Phase II study of Arzerra in front-line CLL were announced. The study examined treatment of ofatumumab in combination with fludarabine and cyclophosphamide (O-FC) in previously untreated CLL patients.

The study added to the growing body of positive clinical evidence for Arzerra in CLL. Arzerra results in patients with CLL that were refractory to fludarabine and another CLL therapy, alemtuzumab, or refractory to fludarabine and had bulky lymph nodes were presented last year. These results became the basis of the first US and EU submissions for Arzerra in the first quarter of 2009. Approvals are still pending.

405 Study – Refractory Follicular non-Hodgkin’s Lymphoma (NHL)

In mid-August, the team also unblinded a study for Arzerra in rituximab refractory follicular NHL. Essentially, researchers were assessing the effectiveness of Arzerra in a very hard to treat from of NHL.

The patients evaluated in this study have a form of NHL that was refractory to rituximab –a standard NHL therapy that targets the same site on cancer cells (CD20) as Arzerra. Many patients in this study were also refractory to standard chemotherapy treatments

409 Study – Front-Line Non-Hodgkin’s Lymphoma (NHL)

The last study to be unblinded was a Phase II study in previously untreated patients with follicular NHL. Arzerra was evaluated in combination with a commonly used regimen called (CHOP) which includes cyclophosphamide, doxorubicin, vincristine and prednisone.

My sincere apologies for the confusion, readers; that's the first and last time I will post in a hurry with pressures of work. Sometimes it is better to post something at leisure and get the facts right than repent in haste. We all make mistakes sometimes, a correction is an appropriate action to take.

A big thank you to Greg at GSK for providing the correct information on the three studies. These guys rock for fast and timely help!

It seems that the data are refering to 2 different trials. The 11% ORR is from a Study of Arzerra in Rituximab Refractory Follicular NHL, whereas the 90% ORR is from results for Arzerra™ in Front Line NHL.
Great Blog! You are my first stop in the morning. Keep up the good work.